The Prime Minister’s mother was asked why her son is alienating voters by pushing gay marriage and replied: “I know, but David just won’t be told”.
The comment, which was reported by The Daily Telegraph, was made at a lunch attended by Mary Cameron.
She was asked why he was pressing ahead with the legislation when it was alienating so many of the Conservative Party’s natural supporters.
Just a few days ago, a long-standing chairman of a local Tory association resigned because of the policy.
Edmund Costelloe, chairman of Somerton and Frome Constituency Conservative Association, had been a party member for 49 years.
Last year it was reported that party membership had plummeted by more than half since David Cameron became leader.
ConservativeHome, a leading website for grassroots Tories, did a poll of the party faithful and found that 71 per cent thought gay marriage was splitting the party.
The policy has also proved deeply unpopular with Conservative MPs, over 130 say they are opposed to the legislation.